1. Field of the Invention
The present invention relates to an abrasive, a method for manufacturing the abrasive, and a method for blast processing with the use of the abrasive. More specifically, the present invention relates to an abrasive used for various sorts of processing such as gloss finishing, glazing, mirror finishing, smoothing or processing of hairline pattern of a surface to be processed of a workpiece, or cutting, cleaning, deburring of the surface to be processed of the workpiece, and a method for manufacturing of the abrasive, and further a method for blast processing to perform a desired process as described above for the workpiece by injecting or projecting the abrasive onto the surface to be processed of the workpiece.
The “a method for blast processing” according to the present invention widely includes not only pneumatic blast processing methods such as a dry blast one and a wet blast one in which the abrasive is injected with the use of compressed fluid such as compressed air, but also blast processing methods capable of projecting the abrasive at a predetermined injection speed or at an injection angle onto the surface to be processed of the workpiece, such as a centrifugal type (impeller type) one in which an impeller is rotated to impart a centrifugal force to the abrasive for projection, and a flat casting type one in which the abrasive is struck with use of a hammering rotor for projection.
2. Description of the Prior Art
As a polishing for improving a surface roughness of the surface to be processed of the workpiece, and for mirror-finishing or gloss-finishing the surface, the polishing with a polishing paper or polishing cloth, the polishing with a buff, lapping, the polishing by contacting with rotating abrasive grains, the polishing by contacting with abrasive grains to which ultrasonic vibration is given, and the like are generally used, but the blast processing is not used. The reason is that satin-finished uneven portions are formed on the surface because the blast processing is one for injecting or projecting the abrasive onto to the workpiece, thereby to cause the abrasive to collide with the surface to be processed of the workpiece.
As described above, generally, the blast processing does not permit the surface of the workpiece to be processed into a glossy surface such as a mirror surface. However, the method for blast processing has been proposed in which the satin surface is prevented from being formed on the surface of the workpiece and the surface of the workpiece can be polished.
For instance, there are grinding and polishing methods as follows. In a grinding method, the abrasives, which are composed by attaching grinding powder to a carrier made of an elastic porous plant fiber with a fat content or a sugar content included in the plant fiber as an adhesive, are mixed with a grinding liquid and then injected numerously onto the surface of the workpiece obliquely for collision. With the carrier plastically deformed, the abrasives are caused to slide on the surface to be processed of the workpiece, and the surface of the workpiece is finished with the grinding powder (refer to Japanese Patent No. 2957492). In a polishing method, the abrasive including a nucleus having desired elasticity and adhesion obtained by containing water and a plurality of abrasive grains adhering to a surface of the nucleus owing to the adhesion is used. And the abrasive is injected onto the workpiece for collision in a state where water is held in the nucleus of the abrasive, and thus, the surface of the workpiece is polished (refer to Japanese Patent Application Laid-Open No. 2001-207160).
Additionally, as an abrasive to make the grinding process as described above possible, a granular abrasive provided with one or a plurality of abrasive grains and an elastic material which is integrally bonded with the abrasive grains and has larger coefficient of restitution than the abrasive grains has been proposed (refer to Japanese Utility Model Application Laid-Open No. S55(1980)-98565)